Rotational Motion Test

Objective

Students will demonstrate an understanding of rotational motion.

Big Idea

Students show off how much they've learned when taking today's unit test on torque, center of mass, angular momentum, and rotational kinetic energy.

Context

Throughout this unit students have developed an understanding of rotational motion, so the goal today is to get students to showcase that knowledge. The design of my test is meant to prepare students for the AP Physics 1 exam and includes questions on torque, center of mass, rotational kinetic energy, and moment of inertia (HS-PS2-1). So after students are settled, they get right into the exam, which requires them to create responses (SP6), justify answers with computations, and qualitatively explain concepts (SP5).

Test Procedures

5 minutes

As students come into the room to take their test, I direct them to look at the screen at the front of the classroom. The screen is displaying their new seats for today, which I've created ahead of time using a random seating chart generator. I used this generator so that I'm not biased in where students are placed and to keep students from relying on their neighbor for answers (also known as cheating).

Once students are seated in their new seats, I review my rules for tests taken in the classroom, which they were given in print at the start of the year. I emphasize that students should not use any outside resources, are only allowed the approved materials, must turn off all electronic devices, and cannot leave the room for any reason at any time. I also inform students that per our school handbook, failure to meet these requirements will result in a zero on the exam and a disciplinary referral.

Before I pass out the exam, equation sheet, and a blank piece of scratch paper, I give the students one more minute to adjust and organize themselves.

Rotational Motion Test

45 minutes

The classroom is absolutely silent while students take their rotational motion test, as I really try to simulate the environment that students experience when taking the AP Physics 1 exam. This means that students' only resource is the AP Equation Sheet and I won't answer many questions during the testing process. While students are testing, I alternate between sitting at the front of the room and walking around the room checking to ensure students aren't cheating.

The test has five multiple choice questions and six short answer questions. The split in the number of question type models the AP Physics 1 exam, because students first experience the multiple choice questions and then the short answer questions on both tests. The content of the multiple choice includes center of mass, torque, moment of inertia, and angular momentum. The short answer questions cover angular speed, angular acceleration, net torque, moment of inertia, and changes in the rotational energy. The test is designed to take just enough time so that students don't feel rushed to finish and while also appropriately challenging them.

The students do quite well on this test, and the average score for the class is 82%. The students who score above average make mostly simple math mistakes. These students are able to apply information from the previous rotational motion and force chapters with ease, and asked strong questions throughout the unit. The students who score about average made a combination of conceptual and computational errors. These students were also less likely to ask questions throughout the unit, but took good notes. There are only two students who fail the test, and it's pretty obvious that they did not arrived prepared. Both of these students are experiencing "senioritis," meaning they have mentally checked out of the class, didn't take notes, and didn't ask questions.